The invention relates to the construction of photocurrent-generating fabrics and coverings, that is to say fabrics that are capable of generating an electric current resulting from sunlight. It also relates to the equipment needed to combine the usual solar protection inherent in the use of shades with the delivery of electricity from the photovoltaic cells.
The photocurrent-generating fabric according to the invention is intended to be used as an outdoor shade, either fixed or windable, for shop windows, glazed bays, terraces, verandas, balconies and loggias, and also as awnings for caravans, camper cars, mobile homes and bungalows, and also as pond and swimming pool covers.
The use of fabric as a shade or equivalent device for providing protection from solar radiation is widely known and well developed, so that there is no need to describe it here in detail. The object of the invention is to profit from the exposure of these fabrics to said solar radiation in order to produce electricity, by incorporating into it a layer of interconnected photovoltaic cells.
There are various difficulties that arise when doing such incorporation, which include effective physical protection of said cells, their interconnection, but also the problem relating to storing the fabric provided with such a layer, insofar as there is a risk of the cells being damaged by being stored.
According to the invention, the photocurrent-generating covering is composed of an array of interconnected solar cells placed in layers. These cells are produced from thin films (the thickness of which is greater than 10 microns) of amorphous silicon, single-crystal or polycrystalline silicon, cadmium telluride, copper indium diselenide or gallium arsenide. They are placed on a rigid substrate, such as glass, ceramic or steel, or on a flexible substrate, such as organic materials or polymers. This multilayer stack includes a molybdenum electrode for the lower electrical contact and a transparent zinc oxide electrode constitutes the upper electrical contact.
This layer of cells is encapsulated in a thermoplastic resin or is covered with a film. This protective film is intended to protect the cells from moisture, to make them resistant to ultraviolet and also to provide electrical insulation.
A multilayer plastic sheet covers the rear side of the layer and protects it from mechanical wear due to it being wound onto a storage support.
The invention therefore also relates to a support for a photocurrent-generating fabric, consisting of an axisymetric tube of uniform polygonal cross section around the periphery of which said fabric is wound. The photovoltaic cells are thus distributed over the fabric in a succession of rows, the spacing between two adjacent rows being chosen in such a way that, when said fabric is stored on the polygonal tube, the cells are kept in a plane parallel to one of the sides that define said polygon. Furthermore, the length of the sides of the polygon making up the tube is greater than the largest dimension of the photovoltaic cells.